Wolverines live in cold places in the far north of the world, in a ring around the north that includes Scandinavia, Russia, Alaska and northern Canada, and they once lived as far south as Colorado, Indiana and Pennsylvania. A wolverine looks like a small bear, but it belongs to the weasel family, and it is the largest land-living member of that family. The scientific name, Gulo gulo, comes from the Latin word for glutton. Wolverines measure 65 to 105 cm in body length, with tails 13 to 26 cm long and shoulders 36 to 45 cm high. An adult male weighs approximately 12 to 18 kilograms (26 to 40 pounds), and adult females weigh approximately 8 to 12 kilograms (17 to 26 pounds), which is less than males.
A wolverine's large paws work like snowshoes on deep snow, and its long, curved claws help it climb. A wolverine walks with its weight mostly on the long bones of its feet, which spreads its weight and helps it travel and hunt in snow.
Wolverines primarily eat meat, but they also eat berries and other plant material, and all year they eat small and medium animals such as voles, squirrels, hares and birds. A wolverine's strong teeth and powerful jaws let it eat even bone. Much of what a wolverine eats comes from animals that have already died. To scavenge is to eat what was left behind, and wolverines eat many kinds of meat, from ground squirrels and rodents to, sometimes, moose or caribou, but more often they scavenge carcasses left by other predators and store them for later. When deep snow keeps a wolverine from hunting large animals, it depends on other big predators for food.
As of November 2026, reports of how far a wolverine may travel in a day differ: up to 25 miles, up to 45 kilometers, or as many as 40 miles. A home range is the area where a wolverine lives and travels. In Europe, a male wolverine's home range runs 100 to 500 square kilometers and a female's 100 to 200, and in Denali National Park the home range of a wolverine may be 100 to 800 square kilometers.
Wolverines are scarce and secretive, so they have been studied less than many other meat-eating animals. In the greater Yellowstone area, wolverines have been studied with live traps, radio tracking and aerial surveys. From 2006 to 2009, researchers documented seven wolverines in eastern Yellowstone and the national forests next to it, and two females each used an average annual range of 172 square miles (447 km2), while three males used 350 square miles (908 km2).
Scientists use cameras that switch on by themselves to find wolverines. In winters 2016 and 2017, researchers in Idaho, Montana, Washington and Wyoming searched random 15-km by 15-km cells with cameras and detected wolverines in 59 of 183 cells, or 34 percent. In that four-state survey, 22,641 of 439,834 photos contained a wolverine, and at many stations most of those photos were of the same wolverine passing the camera again and again. Wolverines are so rarely seen and live so thinly spread in remote country that population trends are hard to judge, and a sudden drop could go unnoticed for years.
Snow is crucial for wolverines: they use it for dens and for keeping food. A mother wolverine builds a den in the snow to give birth to her babies and feed them milk. Most wolverine dens found so far are complexes of snow tunnels built next to boulders or rocks, and a mother can dig a snow den as deep as approximately 15 feet. A 2010 study proposed that wolverines are limited by their need for lasting spring snow for denning and by an upper limit of heat tolerance, and it found that 95 percent of summer and 86 percent of winter tracking locations matched spring snow cover. As of November 2026, new Fish and Wildlife Service research highlights that wolverines depend on areas with persistent spring snow not only for denning and reproduction but also for survival, for example caching food.
The Fish and Wildlife Service's 2018 analysis used a snow depth of more than 0.5 meters on May 1 for wolverine denning, but researchers argued that depth was not conservative enough, and the 2023 analysis raised it to at least 1 meter while keeping the May 1 date. The service also says no snow depth threshold for successful wolverine denning on any date is known, and some researchers suggested snow on May 1 matters less because young wolverines usually leave their dens by mid-March.
Climate models predicted that by 2050 the spring snowpack wolverines need for denning and hunting would remain only in parts of the southern Rocky Mountains, the Sierra Nevada, and greater Yellowstone. In 2018 the service projected snow loss to 2050 for two areas, and its 2023 update projected loss to the end of the century across five areas and found losses would be greater in 2100 than in 2050.
Wolverines mate in summer, but the fertilized egg does not start to grow until early winter, a delay called delayed implantation, so the offspring, called kits, are born between January and April. After a delay of approximately six months, a wolverine's pregnancy lasts only another 30 to 50 days. Delayed implantation lets wolverines have young when food is most plentiful and match the litter size to the food available. Newborn kits are blind and weigh less than one pound at birth, and young wolverines are on their own by approximately five to six months old. Because litters are small and many young die, a female rarely raises more than one young that survives to have young of its own.
The oldest known wolverine fossil, a new species named Gulo sudorus from the Gray Fossil Site in Tennessee, is from the Early Pliocene, between 4.9 and 4.5 million years ago. The earliest wolverine and early fishers, which are also weasel-family animals, both come from North America, which suggests the genus, a related group, may have evolved there and spread to Eurasia later in the Pliocene. Because the fossil site's plants and animals point to a warm, humid climate, a 2018 study suggests wolverines may have become adapted to cold only relatively recently. The same study found that Plesiogulo, often thought to be the wolverine's ancestor, is probably not closely related to it and may instead show a similar way of life evolving separately.
DNA studies disagree on when wolverines split from their closest relatives: one put the split between the wolverine's genus, Gulo, and another genus, Martes, at approximately 6.4 to 6.3 million years ago, and another at approximately 5.6 million. Scientists recognize two wolverine subspecies, the North American wolverine and the European wolverine, which differ mainly in their genes. A population on Vancouver Island, Canada, has skull differences from mainland wolverines and may be another subspecies, but its status had not been decided.
Wolverines were nearly gone from Montana in the early 1900s and have been increasing in numbers and range since, with recovery starting in the northwest of the state. Trapping and predator control reduced the wolverine's range in the lower 48 states by the 1930s, and some recovery has happened since. The Fish and Wildlife Service found that unsustainable trapping in southern Canada appears to have lowered the wolverine population in part of southern British Columbia and Alberta, and trapping was later closed along the U.S.-Canada border in British Columbia.
A 2023 genetic study covering the U.S.-Canada border looked at 887 individuals, and it found low genetic diversity and increasing fragmentation at the southern edge of the range, and that highways in southern British Columbia appeared to restrict females moving from Canada to the U.S. Wolverines live at low numbers everywhere in their range, because each one needs a very large home range. As of November 2026, a 2017 to 2022/23 count put Europe's wolverines at approximately 1,300, in two groups: approximately 900 in Scandinavia, which is stable, and approximately 400 in Karelia, which is increasing.
As of November 2026, the U.S. Fish and Wildlife Service proposed listing the wolverine as threatened in 2013, decided in 2020 that listing was not warranted, was told by a Montana court in 2022 to reconsider, and finalized the listing in November 2023. Canada listed the wolverine as a species of special concern in 2018, and in Montana wolverine trapping was suspended before listing, with a statewide quota of zero. A wolverine's conservation status depends on the scale: it is Least Concern worldwide on the IUCN Red List, though European populations are at higher risk, and threatened under U.S. law in the lower 48 states.
Wolverines usually live alone, and they stay active all year and do not hibernate. In the wild, wolverines usually live 5 to 7 years, and a few reach 13, and in zoos, some have lived to 17. Wolverines can climb trees quickly and are excellent swimmers.
Words to know
- genus: a related group
- Pliocene: an ancient time
- subspecies: a regional type
- fragmentation: broken-up habitat
- snowpack: lasting snow
- scavenge: eat leftovers
